A flat vibration motor is a miniature motor that can be installed in cellular phones, smart phones, personal digital assistants (PDA), and similar mobile telecommunication terminals and various other electronic devices. When a signal is received from a call center, a flat vibration motor can alert a user of an incoming call through vibrations instead of sound.
More specifically, when set in “manner mode”, a mobile telecommunication terminal transmits vibrations through the operating of such a flat vibration motor.
A flat vibration motor is coin-sized and generates a strong vibrating force, so that it requires a relatively durable coupling structure. However, its terminals are often deformed due to the strong vibrating force, so that the contact points are altered.
FIG. 1 is a perspective view of a flat vibration motor according to the related art.
Referring to FIG. 1, a flat vibration motor according to the related art includes a stator portion 10, a rotor portion (inside the stator portion), and a base portion 30.
The stator portion 10 forms a housing within which the rotor portion is rotatably disposed, so that vibrating force imparted by the rotor portion can be transmitted to the outside. Also, the stator portion 10 has a second circuit board 40 for transmitting electricity to the rotor portion, and a fixing mount 13 extending from a side thereof. Here, the second circuit board 40 is supported by the fixing mount 13 on the stator portion 10.
The base portion 30 has a terminal 50 through which electricity is transmitted from an external source, and is coupled to the stator portion 10. The terminal 50 is connected to the second circuit board 40 on the fixing mount 13.
In further detail, the bottom part of the terminal 50 is fixed with solder 80 between the bottom surface of the base portion 30 and the second circuit board 40 on the fixing mount 13.
The base portion 30 is coupled to the stator portion 10 with an adhesive 90.
Here, after the base portion 30 is assembled, during the fixing process of the terminal 50 to the second circuit board 40 using solder 80, many problems can arise.
The terminal 50 is fixed at its lower portion with solder 80 to the second circuit board 40, while its remainder is exposed to the outside. Accordingly, when the terminal 50 is subjected to external forces during manufacturing or load while being installed on a device such as a mobile telecommunication terminal, the solder 80 portion of the terminal 50 can be deformed or detached, resulting in an altering of the contact point between the terminal 50 and an external terminal.
When even a slight force is applied when the solder has not hardened, the coupled region can easily be deformed. Liquid solder can be deposited by a solder iron during the soldering process on other regions of the flat vibration motor. In these two cases, a faulty contact problem between terminals can occur. Additionally, the outer appearance of the product is compromised giving the impression of inferior quality.
Also, the base portion 30 can be deformed or burnt by excess heat that is generated during the soldering process, impeding efforts to lower product defect rates.
Moreover, the base portion 30 and the stator portion 10 that are coupled with the adhesive 90 may become loose or disengage due to ineffectiveness of the adhesive 90 or a from an externally-applied shock, such as one from a user dropping the mobile telecommunication terminal.
When such a problem of coupling the stator portion 10 and the base portion 30 occurs, it can induce a problem in the connection between the terminal 50 and the circuit board 40, and disrupt the supply of electricity.
FIG. 2 is an exploded perspective view showing a disassembled state of the base portion 30 and terminals 50 from the stator portion of the flat vibration motor in FIG. 1.
Referring to FIG. 2, the fixing mount 13 is in the form of a rectangular plate extending from a side of the lower case 12, and the second circuit board 40 is disposed on the top surface of the fixing mount 13.
The terminal 50 is formed of a contacting portion 52, an elastic portion 54, and a joining portion 56. The joining portion 56 is inserted and fixed between the second circuit board 40 and the base portion 30, and is soldered and coupled to a conducting portion 40a of the second circuit board 40.
However, with only the joining portion 56 of the terminal 50 fixed (as shown in FIG. 2), the elastic portion 54 and the contacting portion 52 are not supported by a wall of the base portion 30 and are exposed to the outside. Therefore, when the terminal 50 is compressed, it lacks support or protection from external forces.
When a flat vibration motor with the above-described structure is installed in a device such as a mobile telecommunication terminal, the contacting portion 52 contacts a power terminal of the device to be supplied with power. Here, the contacting portion 52 and the elastic portion 54 generate a certain amount of pressure at the joining portion on the power terminal.
However, because the elastic portion 54 cannot be supported on all four sides, if a load is applied in a predetermined direction on the elastic portion 54, it is prone to warp or permanently compress, altering a contacting position with a power terminal of a mobile telecommunication terminal. In this case, during product manufacturing, assembly defects can occur.
Additionally, when the terminal 50 is unable to withstand a certain amount of pressure and is deformed in the direction of the open side of the base, its elasticity decreases, so that cannot maintain an adequate pressure for contacting an external terminal.
Furthermore, a flat vibration motor according to the related art has somewhat complex manufacturing and assembling processes.